1. Field of the Invention
The present invention relates to cylinder head lubricating structure for an engine, comprising: a crankcase forming a crank chamber storing therein oil, and rotatably supporting a crankshaft; a cylinder head connected to the crankcase with a cylinder block interposed therebetween, the cylinder head having an intake valve and an exhaust valve disposed therein to be capable of opening and closing; oil splashing means housed in the crank chamber so as to splash the oil in accordance with rotation of the crankshaft; and a breather passage formed in the crankcase, the cylinder block and the cylinder head to guide, toward the cylinder head, gas including oil mist generated in the crank chamber by the oil splashing means, and in which lubricating oil is supplied toward the cylinder head through the breather passage.
2. Description of the Related Art
The following cylinder head lubricating structures for engines have already been known through Japanese Utility Model Application Laid-open No. 58-156113 and Japanese Utility Model Publication No. 60-6585, and the like. In the cylinder head lubricating structures for engines, gas including oil mist splashed by oil splashing means is guided toward a cylinder head through a breather passage by using pressure fluctuation in a crank chamber, thereby using the oil mist for lubricating a valve operating mechanism for operating an intake valve and an exhaust valve provided in the cylinder head.
Now, to guide the oil mist generated in the crank chamber toward the cylinder head through the breather passage by using pressure fluctuation in the crank chamber, required is a one-way valve which prevents backflow of the oil mist toward the crank chamber. Each of the structures disclosed in Japanese Utility Model Application Laid-open No. 58-156113 and Japanese Utility Model Publication No. 60-6585 includes a one-way valve provided to a head cover forming a valve operating chamber between the head cover and the cylinder head, the valve operating chamber housing a valve operating mechanism for opening and closing the intake valve and the exhaust valve.
In such a conventional cylinder head lubrication structure, when the head difference from the crank chamber to the cylinder head is large, the oil may flow backward from the middle of the breather passage toward the crank chamber, and, in such a case, it is difficult to supply a sufficient amount of oil to the cylinder head side.